EP0285593B1 - Verfahren zur Erhöhung des Korrosionswiderstandes eines gehärteten und selbstangelassenen Armierungsstahlstabes - Google Patents

Verfahren zur Erhöhung des Korrosionswiderstandes eines gehärteten und selbstangelassenen Armierungsstahlstabes Download PDF

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Publication number
EP0285593B1
EP0285593B1 EP88870053A EP88870053A EP0285593B1 EP 0285593 B1 EP0285593 B1 EP 0285593B1 EP 88870053 A EP88870053 A EP 88870053A EP 88870053 A EP88870053 A EP 88870053A EP 0285593 B1 EP0285593 B1 EP 0285593B1
Authority
EP
European Patent Office
Prior art keywords
bar
process according
layer
self
deposited
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP88870053A
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English (en)
French (fr)
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EP0285593A1 (de
Inventor
Jacques Defourny
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Centre de Recherches Metallurgiques CRM ASBL
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Centre de Recherches Metallurgiques CRM ASBL
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Priority to AT88870053T priority Critical patent/ATE63957T1/de
Publication of EP0285593A1 publication Critical patent/EP0285593A1/de
Application granted granted Critical
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/73—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/08—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires for concrete reinforcement
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/10—Oxidising
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
    • E04C5/01—Reinforcing elements of metal, e.g. with non-structural coatings
    • E04C5/015—Anti-corrosion coatings or treating compositions, e.g. containing waterglass or based on another metal

Definitions

  • the present invention relates to a method for improving the corrosion resistance of a hardened and self-tempering steel rebar.
  • the steel bars used for the reinforcement of concrete are subjected to corrosion both during their storage, their transport and their implementation on construction sites as during their lifetime in concrete.
  • a first type of technique consists in applying a protective film to the concrete intended to prevent the penetration and diffusion of atmospheric agents in the concrete.
  • This film applied to the finished part or construction, however, does not provide any protection for the reinforcement during its storage, transport or use.
  • its protective action may diminish or even disappear over time under the effect of atmospheric erosion. Finally, this action is compromised in the event of degradation or damage to the protective film.
  • the second type of technique consists in depositing, on the reinforcement, a layer of protection against corrosion, for example by dip galvanizing or by coating with epoxy resin.
  • the first document briefly describes the formation of a layer of phosphate, respectively of oxide, on a piece of steel during the quenching by addition of manganese phosphate, respectively of KMnO4, to the quenching bath.
  • the second document discloses a process for forming a resin layer on a preheated steel rebar.
  • the object of the present invention is to provide a method for protecting concrete reinforcements against corrosion, which does not have the aforementioned drawbacks and which, in particular, can be implemented during the manufacturing process of these reinforcements.
  • the present invention relates to steel concrete reinforcements subjected to the quenching and self-tempering process which was recently developed by the same applicant BE A 889 575.
  • the first step consists in subjecting a steel bar, as soon as it leaves the last stand of the hot rolling mill and therefore from its end of rolling temperature, that is to say in the austenitic state, to abrupt and short-term surface cooling such that it causes in the bar the formation of a peripheral layer consisting of martensite or bainite, that is to say a quenching structure.
  • This first cooling is carried out with cold water.
  • the surface of the bar is at a temperature below the point Ms of the steel used, while the core of the bar is not reached by the sudden cooling.
  • the bar is then, during a second step, subjected to cooling in the air during which the temperatures are equalized in its section: the surface temperature increases under the effect of the heat coming from the heart, this which causes self-tempering of the surface layer of martensite or bainite; simultaneously, the core cools slowly and its initial austenitic structure is transformed into ferrite and carbides.
  • surface and core temperatures are approximately equal to between 400 degrees centigrade and 700 degrees centigrade. From the equalization of the temperatures, the bar cools, throughout its section, to room temperature, without undergoing any further structural transformation. This latter cooling constitutes the third stage of this known process.
  • the present invention makes it possible to take advantage of the particular conditions which this process presents to achieve the aim aimed at, namely the improvement of the corrosion resistance of this type of concrete reinforcement.
  • the invention also relates to a rebar having improved protection against corrosion obtained by applying this method.
  • a method for improving the corrosion resistance of a steel rebar subjected to a continuous heat treatment comprising a first step which consists in surface hardening of the bar from the end temperature rolling, a second step which consists of cooling in air with temperature equalization in the section of the bar and self-tempering of the hardened surface layer, and a third step which consists of a final cooling of the bar in the air from the equalization temperature to ambient temperature, is characterized in that during at least one of said steps, a protective layer is formed on the surface of the bar made up of a chosen material in a group comprising phosphates, oxides, paints and synthetic resins.
  • said phosphating treatment is applied during the first step of the process, by adding the phosphating agent to the cooling water.
  • said phosphating treatment is applied during the second step of the process, by projecting onto the surface of the bar a liquid or gaseous fluid containing said phosphating agent.
  • said phosphating treatment is applied during the third step of the process by immersing the bar in a solution containing said phosphating agent.
  • the above-mentioned phosphating treatment is preferably applied continuously to a moving bar, it would not, however, depart from the scope of the present invention to carry out this treatment discontinuously during the third step of the process mentioned above.
  • the treatment could for example relate to a plurality of bars, cut to an appropriate length and immersed in a solution of phosphating and possible pickling.
  • a stable oxide layer is formed on the bar, by exposing said bar to an oxidizing gas stream such as air or oxygen.
  • this operation is advantageously carried out in the process zones where the surface of the bar has a high temperature, that is to say before the start of the first step and / or between the second and the third step, in the sense defined above.
  • a layer of paint resistant to high temperatures is deposited on the surface of the bar.
  • this layer of paint is advantageously deposited by spraying, this deposit preferably being carried out between the first and the second stage of the process, that is to say in the zone thereof where the surface of the bar is at a low temperature.
  • the paint is then quickly annealed and dried at high temperature during the surface reheating of the bar which occurs during the second stage of the process.
  • a thin film of plastic resin is deposited on the bar, for example of the type soluble in water and used in other applications as additives to concrete to make it impermeable to moisture.
  • this resin film is advantageously deposited by projection or immersion during the third step in the sense defined above.
  • an oil film is deposited on said protective layer consisting in particular of phosphate, oxide, paint or resin.
  • a desiccant oil is preferably used.
  • a desiccant oil remains fluid and oily for a period which depends on its composition; it thus very effectively protects said layer against any external agent and it thus clearly reinforces the protection provided by the phosphate, oxide, paint or resin layer.
  • the oil dries and therefore does not alter the behavior, in particular, the adhesion of the bar in concrete.
  • an operating sequence corresponding to a pickling treatment followed by a manganese phosphating is described below, applied to a bar during the third step of the quenching and self-tempering process.
  • the bar was immersed for about 10 min in a pickling solution consisting of 0.5 N HCl supplemented with 2.5 g / l of hexamethylenetetramine, which was at room temperature.
  • a pickling solution consisting of 0.5 N HCl supplemented with 2.5 g / l of hexamethylenetetramine, which was at room temperature.
  • the bar was immersed in an aqueous solution containing 10% by weight of a phosphating agent, the temperature of the solution was between 90 ° C and 95 ° C, the ratio of total acidity to free acidity was 7: 1 and the immersion time was approximately 10 min.
  • the bar phosphated was coated with an oil film by soaking in an oil bath at room temperature.
  • the bar thus treated showed no trace of oxidation during prolonged storage and exposure to an industrial atmosphere.
  • the method of the invention is implemented during the quenching and self-tempering process. It does not require significant additional equipment and it provides both temporary protection against atmospheric corrosion and permanent protection against corrosion in concrete. Finally, it would not be outside the scope of the present invention to apply simultaneously or successively several of the aforementioned variants, during the quenching and self-tempering process of the bar.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Architecture (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacturing & Machinery (AREA)
  • Structural Engineering (AREA)
  • Civil Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Heat Treatment Of Steel (AREA)
  • Reinforcement Elements For Buildings (AREA)
  • Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)

Claims (10)

1. Verfahren zur Verbesserung des Korrosionswiderstandes eines Stabs aus Armierungsstahl, der einer kontinuierlichen thermischen Behandlung ausgesetzt wird, bestehend aus einer ersten Stufe, die in einer Oberflächenabschreckung des Stabes ab der Endtemperatur des Walzens besteht, einer zweiten Stufe, die aus Abkühlen an der Luft mit Temperaturausgleich im Stabquerschnitt und Selbstvergütung der abgeschreckten Oberflächenschicht besteht, und einer dritten Stufe, die in einem abschliessenden Abkühlen des Stabes an der Luft von der Ausgleichstemperatur bis zur Umgebungstemperatur besteht, dadurch gekennzeichnet, daß man im Verlauf mindestens einer dieser Stufen an der Staboberfläche eine Schutzschicht aus einer Substanz bildet, die ausgewählt ist aus der Gruppe Phosphate, Oxide, Lacke und synthetische Harze.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man für die Phosphatierung der Staboberfläche ein Phosphatierungsmittel mit einem Gehalt an Manganphosphat verwendet.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß man vor oder während der besagten Phosphatierungsbehandlung des Stabes einen Beizvorgang durchführt.
4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man auf dem Stab eine stabile Oxidschicht ausbildet, indem man einen oxidierenden Gasstrom auf besagten Stab einwirken läßt.
5. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man auf der Staboberfläche eine bei erhöhten Temperaturen widerstandsfähige Lackschicht aufbringt.
6. Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß man jene Lackschicht mittels Spritzen aufbringt.
7. Verfahren nach Anspruch 5 oder 6, dadurch gekennzeichnet, daß man jene Lackschicht auf der Staboberfläche unmittelbar nach dem Abschreckschritt jenes Abschreck- und Selbstvergütungvorgangs aufbringt.
8. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man eine Harzschicht in flüssigem Zustand auf der Staboberfläche aufbringt.
9. Verfahren nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß man einen Ölfilm auf jener Schutzschicht aufbringt.
10. Abgeschreckter und selbstvergüteter Stab aus Armierungsstahl, der mit einer Korrosionsschutzschicht versehen ist, die mittels eines Verfahrens nach einem der vorhergehenden Ansprüche gebildet wird.
EP88870053A 1987-04-03 1988-03-29 Verfahren zur Erhöhung des Korrosionswiderstandes eines gehärteten und selbstangelassenen Armierungsstahlstabes Expired - Lifetime EP0285593B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88870053T ATE63957T1 (de) 1987-04-03 1988-03-29 Verfahren zur erhoehung des korrosionswiderstandes eines gehaerteten und selbstangelassenen armierungsstahlstabes.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BE8700353 1987-04-03
BE8700353A BE1000432A6 (fr) 1987-04-03 1987-04-03 Procede pour ameliorer la resistance a la corrosion d'une barre d'armature en acier trempe et auto-revenu.

Publications (2)

Publication Number Publication Date
EP0285593A1 EP0285593A1 (de) 1988-10-05
EP0285593B1 true EP0285593B1 (de) 1991-05-29

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ID=3882602

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88870053A Expired - Lifetime EP0285593B1 (de) 1987-04-03 1988-03-29 Verfahren zur Erhöhung des Korrosionswiderstandes eines gehärteten und selbstangelassenen Armierungsstahlstabes

Country Status (5)

Country Link
EP (1) EP0285593B1 (de)
AT (1) ATE63957T1 (de)
BE (1) BE1000432A6 (de)
DE (1) DE3862982D1 (de)
ES (1) ES2023510B3 (de)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2659356B1 (fr) * 1990-03-07 1995-02-17 Liesse Maurice Procede de protection de surface par voie chimique d'objets metalliques.
JP2654268B2 (ja) * 1991-05-13 1997-09-17 株式会社東芝 半導体装置の使用方法
CH689307A5 (de) * 1995-04-13 1999-02-15 Cement Intellectual Property L Verfahren sowohl zur Korrosionsinhibierung, wie auch zur Verstärkung der Verbundeigenschaften von Armierungsmetallen.
AU2003263415A1 (en) * 2002-04-26 2003-11-10 Liuzhou Construction Machinery Factory General Corrosion resistant prestressed steel bar and its preparing process
GB201409337D0 (en) * 2014-05-23 2014-07-09 Fry Andrew A floor screed reinforcement a method of using such reinforcement to produce a screeded floor

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE737025C (de) * 1939-06-21 1943-07-05 Metallgesellschaft Ag Abschreckmittel fuer erhitzte Metalle
DE889575C (de) * 1951-06-26 1953-09-10 Dynamit Nobel Ag Schlagwettersichere elektrische Zuendpillen
DE1153589B (de) * 1957-03-21 1963-08-29 Jenolite Ltd Verfahren zur Behandlung der Oberflaeche von Gegenstaenden aus Eisenmetallen, die in Beton eingebettet werden
GB2041783B (en) * 1979-02-23 1983-05-11 Sumitomo Metal Ind Surface-coated nonmagnetic steel material

Also Published As

Publication number Publication date
EP0285593A1 (de) 1988-10-05
ES2023510B3 (es) 1992-01-16
DE3862982D1 (de) 1991-07-04
BE1000432A6 (fr) 1988-12-06
ATE63957T1 (de) 1991-06-15

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